With Kakuro, it is as important (if not more so)
to know what is not there as what is. So, below is the table of the
unique sets if numbers (such as 16 in 5 cells), along with the set of numbers
that are not in there (ie, 5, 7, 8 and 9).

Click here to see the table of all of the number sets and here for a table of all of number that always appear in sets.